This invention relates to the construction of concrete piling and more particularly to a method of constructing, on the site, a structure foundation which includes one or more concrete piles post-stressed to the pile cap to form a rigid unitary foundation for a structure, such as an electrical transmission line tower, that may be subjected to severe overturning moments or uplifting forces as well as the downward gravity loads. The invention is particularly valuable for use in the construction of transmission line towers in remote areas where all construction material may be transported to the site by helicopters, thereby obviating the need for costly access roads.